West End debut ... Whoopi Goldberg is set to play Mother Superior in Sister Act. Photograph: Timothy White/PA

Sister Act: The Musical is in no way like Sister Act: the movie. At least, that's what the production team were at pains to tell us when it opened last summer. It had a brand-new book, by the writers of Cheers, and brand-new music, by the award-winning Alan Menken. On film, the heroine is an averagely-talented Vegas singer who's the wrong side of 30, and has a gangster boyfriend who won't leave his wife; on stage, she is pouting, gifted young thing in her twenties, singing in a club straight out of a blaxploitation movie under the controlling gaze of her smooth-talking, sex-fuelled boyfriend. On screen, the choir nuns can't sing at all; in the theatre they've been forced into singing quietly and demurely by the Mother Superior before Deloris convinces them to raise their voices. It could barely be clearer that they are two separate entities.

Except, now, not. Some 18 years after the film opened, Whoopi Goldberg has announced that she will appear in the show for a limited three-week run from 10 August. She'll be playing the role of Mother Superior, following in the footsteps of Maggie Smith and Sheila Hancock.

Admittedly she has never been that far from the show:

She came on stage at press night last year to take a curtain call with Patina Miller, her successor as Deloris. And the voiceover before the curtain rises, reminding us to switch off our mobile phones? That's her too. Still, Goldberg's appearance in the show has brought the barriers between film and stage crashing down.

Queen have been threatening to do something similar since We Will Rock You opened – a silhouette of Freddie Mercury is visible on the posters for the show, and Brian May and Roger Taylor turn up to do a special guest appearance at every possible occasion. What next? Benny and Bjorn from Abba to turn up in the orchestra pit for Mamma Mia? Well, I have a few thoughts ...

• Jennifer Grey to star in Dirty Dancing as Baby's mother: 23 years after the original film, not hard – although cosmetic surgery means that she no longer bears any resemblance to herself in 1987.

• Reese Witherspoon to reprise her role in Legally Blonde as Elle: OK, so she's a tad older than a sorority president might usually be, but with good wigs and makeup, surely nobody will notice the difference. And let's face it: she'll be a bigger box-office draw than Jennifer Ellison, who recent reports – since denied – suggested was to replace Sheridan Smith in the role later this year.

• Terence Stamp to reclaim the lead as Bernadette in Priscilla Queen of the Desert: Priscilla aficionados were brokenhearted when Tony Sheldon, who originated the stage role, left the London production. Maybe only the man who originally played the part on film could replace him in their affections? Yes, he's 70 now, but as with Witherspoon, with good wigs and thick makeup - frankly part of the job when you're in Priscilla - who would know?

• John Travolta to guest-star in Grease as Teen Angel: He can't be doing that much at the moment, so he'd need little convincing to don a white suit (and he's good in a white suit, we know that) and trill out Beauty School Dropout every night.